Beside the ruined Valley of Peace, Sadr's men wait for martyrdom

In a dirty alley on the outskirts of the old city of Najaf yesterday stood a crowd of militia fighters - the newest volunteer among them a bright young biology student called Ali.

He arrived seven days ago, bearing a Kalashnikov, a green silk bandanna and a willingness to fight for the radical Iraqi cleric Moqtada al-Sadr.

On his chest was a green ammunition belt, filled with loaded magazines and rusted hand-grenades. Written neatly on the belt was his name, address and telephone number. "In case I die, so they can reach my family," he said.

Like all of the fighters in this group on the front line, Ali, 26, came across country from Amara, one of several southern Iraqi towns where Mr Sadr's Shia militia has fought in the past week, including yesterday when British troops said 10 fighters were killed.

Most who take up arms for the 30-year-old Mr Sadr are young and poor. A minority, like Ali, are also well educated.

They revile Saddam Hussein, who persecuted them, but their eagerness to fight now is largely born out of frustration that the war and occupation has brought little material change to their lives.

Added to this is their avowed religious conviction. "I came for the defence of Islam," Ali said. He and the other 20 or so fighters in his platoon describe themselves as an "Islamic resistance".

Ali and his colleagues spent most of yesterday taking cover in the shade. From a window in a building above them a sniper fired out a round every few minutes into the Valley of Peace cemetery, just 100 metres away.

On the far side of the vast cemetery are 2,000 US Marines, who have threatened to seize control of the city. Last night their commander said his troops were making the "final preparations" for an attack, though an early onslaught was delayed at the last minute, according to the New York Times. One of Mr Sadr's associates warned that vital oil pipelines in southern Iraq would be blown up if the US attacked Najaf.

Occasionally a US attack helicopter passed nearby and the fighters fired off rounds from their machine guns and Kalashnikovs inexpertly. There were several command wires leading out to bombs hidden in the cemetery, ready to ambush American forces when they advanced.

The entire scene was imbued with deep religious overtones and constant references to the Imam Ali, the Prophet Muhammad's son-in-law and a key figure in the Shia sect. "Ali is with you," they said to each other in greetings.

"Do you think I aim when I shoot this thing?" one machine gunner said to another fighter. "All these things are done by Imam Ali. All I have to do is carry the thing and pull the trigger and he will help me with my aim and bring down the helicopter. It is not me that does these things."

The other Shia parties hold little appeal for the fighters. "They just use Islamic slogans to cover up what they are doing," said Ali. "Syed Moqtada is a nationalist and he demands the rights of the Iraqi people and the rights of the poor. He is the only one who didn't betray the people and co-operate with the Americans."

The fighters here in Najaf have rallied behind Mr Sadr, the scion of a highly respected clerical family, because unlike all other leading Shia political leaders he has so far shunned involvement in the pro-American governments. Although his radicalism is rejected by many middle-class Shias, he carries a broad appeal for those looking for a revolutionary streak in the Shia faith in Iraq. It was his father's cousin, Muhammad Baqr al-Sadr, who began the activist, or "spoken", school in Najaf's Shia clerical community, advocating an Islamic state through revolution until he was killed in 1979.

Moqtada's father, Muhammad Sadiq al-Sadr also acquired a reputation as a social activist until he was assassinated in 1999. Since last year's invasion his son has sought to claim that activist's mantle too.

It is an appeal that for months after last year's invasion the US and British occupation authorities seriously underestimated. Now Mr Sadr is leading his second uprising in just five months.

For the past week Najaf, site of the holiest shrine in the Shia faith, has been the focus of fighting, but there have been clashes in Baghdad and in southern towns that have challenged the new government.

In an acknowledgement of the sensitivity of the conflict, Ibrahim al-Jaafari, one of Iraq's two vice presidents and leader of the biggest Shia party, the Da'awa, yesterday said US troops should stop fighting in Najaf and leave the job to Iraqi se curity forces.

The militia will be waiting - galvanised by the words of Mr Sadr, who has urged the fighters to continue even if he is killed or captured.

Every few hours yesterday a cleric in the gold-domed Imam Ali shrine, in the heart of the old city, issued exhortations and just after 1pm the fighters pulled out sheets of cardboard, took off their ammunition belts and headscarves and knelt to pray. Then they sat in the shade, eating grapes stored over ice in a coolbox.